The present invention relates to a golf ball having an excellent low temperature impact resistance.
Golf balls using ionomer resins in the cover have excellent cut resistance, durability and flight characteristics as compared with golf balls using a balata cover, and have established the status as golf balls of first-class make for several years.
The ionomer resins sold under the trademark "Surlyn" by the E. I. DuPond de Nemours Company are generally employed as cover materials of golf balls. These resins are ionic copolymers of ethylene and a metal salt of an unsaturated carboxylic acid, and there are various grades of polymers such as the sodium ion type and the zinc ion type.
Golf balls using an ionomer resin of a single ion type as a cover material have the drawback of cracking when struck by a golf club at low temperatures. In order to eliminate to this drawback, it is proposed to employ as a cover material a mixture of at least two different ionomer resins, e.g. a mixture of a sodium ion type ionomer resin and a zinc ion type ionomer resin. However, the proposed cover composition has the disadvantages that the fatigue fracture of the golf ball due to repeated impacts is hastened and also the degree of freedom in designing the cover characteristics is lowered because the kinds of the resins to be blended are restricted.
It is an object of the present invention to provide a golf ball having an excellent low temperature impact resistance.
A further object of the invention is to provide a golf ball having an excellent low temperature impact resistance as well as other properties by a simple method as compared with a conventional golf ball using a mixture of different ionomer resins as a cover material.
These and other objects of the present invention will become apparent from the description hereinafter.